Definition
Homicide per infortunium is the accidental killing of another person during the course of a lawful act, committed without any intention of harm. It is a species of excusable homicide — meaning that although a death resulted, the law treated the actor as blameless and excused rather than justified the killing. The classic formulation requires two conditions: (1) the actor was engaged in a lawful activity at the time of the killing, and (2) there was no intent, however remote, to cause harm to the person killed.
The Latin phrase translates literally as "homicide by misfortune." It belongs to the common law taxonomy of homicide, which sorted killings into felonious (murder, manslaughter) and non-felonious (excusable, justifiable) categories. Homicide per infortunium occupied the excusable category alongside se defendendo (killing in self-defense).
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Common Confusion
Homicide per infortunium is closely related to, and often confused with, homicide per misadventure. The two terms were historically used interchangeably in many authorities — Burrill explicitly notes they are called by both names — and the practical distinction, if any, was never settled in the common law. Researchers should treat both terms as functionally equivalent and search both when working in historical sources. Neither maps cleanly onto any single modern offense or defense category; the excusable/justifiable framework they belonged to has been substantially reorganized in modern criminal codes.
Also compare homicidium ex casu, the civil law counterpart referenced by Burrill. The concepts are analogous but arise from different legal traditions; conflating them in early sources can produce research errors.
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Why It Matters in Research
This is primarily a historical and terminological term rather than an operative modern legal concept. Researchers will encounter it almost exclusively in pre-twentieth-century materials — treatises, early American case reporters, English common law sources, and criminal law digests drawing on Blackstone and Stephen.
Several research traps are worth flagging:
The term does not translate directly into any modern statutory category. Contemporary criminal law handles accidental killings through the absence of mens rea, involuntary manslaughter, or negligent homicide frameworks. When a historical source excuses a defendant on grounds of homicide per infortunium, the modern equivalent is closer to an acquittal for lack of criminal intent than to any affirmative defense.
The lawful-act requirement is load-bearing and easily missed. Common law authorities were careful to distinguish homicide per infortunium (lawful act, no intent) from manslaughter (unlawful act, or lawful act done in an unlawful manner). If the actor was engaged in an unlawful activity, or even a lawful activity pursued recklessly, the death could be elevated to manslaughter. This distinction matters when reading early case law: courts often turned on this precise boundary.
Rapalje & Lawrence redirect the reader to their general HOMICIDE entry rather than defining the term independently — a common approach in 19th-century digests for subspecies terms. Researchers using that dictionary should follow the cross-reference and read the full typology.
The term appears across English and American sources with near-identical definitions, suggesting heavy derivation from Blackstone (4 Bl. Comm. 182) and Stephen (4 Steph. Comm. 101). When tracing a historical argument about accidental homicide, these two treatise references are the common ancestry of most dictionary and digest entries and should be consulted directly.
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Historical Dictionary Support
All three source dictionaries converge on a consistent definition: accidental killing during a lawful act, without intent, classified as excusable homicide. Black's and Burrill reproduce essentially identical language, both citing Blackstone and Stephen as authority. This uniformity reflects the term's doctrinal stability — it was not contested but rather inherited wholesale from English common law.
Burrill adds the most useful additional material: he notes the synonym homicide per misadventure, cites Russell on Crimes and Wharton's American Criminal Law, and draws the parallel to the civil law homicidium ex casu. This cross-tradition note is the most substantive differentiation among the three sources.
What the historical dictionaries do not address is the gradual dissolution of this category in American criminal law. As states codified their criminal codes through the 19th and 20th centuries, the common law excusable/justifiable/felonious taxonomy gave way to statutory frameworks organized around mens rea levels. The term appears in older treatises and reporters but is largely absent from modern statutory text. None of the dictionaries mark this transition because they were written before it was complete.
Rapalje & Lawrence's cross-reference approach, while unhelpful for a quick lookup, reflects sound editorial judgment: the term's meaning is only intelligible within the broader typology of homicide, and isolating it from that taxonomy risks misunderstanding.
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Jurisdictional Note
Homicide per infortunium was a common law category operative across English and early American jurisdictions. Its relevance in American courts declined as state legislatures codified criminal law, with the pace and extent of displacement varying by jurisdiction. Researchers working in pre-codification materials from any American state or in English sources through the 19th century will find the term operative; in modern statutory research, it has no direct application.
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